Weekend work of python 2

Requirements:
# 1. Users give their accounts charge money: for example, to charge 3,000 yuan.
# 2 page displays the serial number + name + price, such as:
# # [=========== following commodity for you to choose: ===========]
## No. Name price
# 1 # 1999 PC
# 2 mouse # 10
# 20 # yacht 3
# 4 # 998 beauty
# N # n-cart or billing
# q or Q to exit the program (e.g., billing cart can not exit)]
# [== ========================================]
# cart settlement
# 3. user input select the product number, and then print trade names and commodity prices, and this product, add to cart, the user can continue to add products.
# 4. If the product number entered by the user is incorrect, you are prompted an error, and re-enter.
# 5. (1) user input n for the shopping cart settlement, in order to display the user inside the shopping cart of goods, quantity and unit price
# (2) If the amount of money is insufficient recharge allow users to delete an item until it can be purchased, if recharge plenty of money, you can purchase exit
# (3) after exiting the program, followed by the display of items purchased, quantity, unit price, and the total of how much money to spend, how much the balance of the account
# 6. user input Q or q to exit the program .

Can be divided into modules on the line to write,

# Product List

goods_list = [
    {"name": "电脑", 'price': 1999},
    {"name": "鼠标", 'price': 10},
    {"name": "游艇", 'price': 20},
    {"name": "美女", 'price': 998},
    {"name": "油精", 'price': 30},
]

# Initial Amount

money = 0

# Cart (you ask cart, showing roughly what it was like)

car = {}
'''
car = {
    1: {"name": "电脑", 'price': 1999},
    2: {"name": "鼠标", 'price': 10},
    3: {"name": "游艇", 'price': 20},
    4: {"name": "美女", 'price': 998},
    5: {"name": "油精", 'price': 30},
}
'''

# Recharge

def chongzhi():
    global money
    while 1:
        MONEY1 = the INPUT ( ' Enter the amount you want to recharge: ' ) .strip ()
         IF money1.isdigit ():
            MONEY1 = int (MONEY1)
            Money + = MONEY1
             Print ( ' successful recharge, recharge amount of this element% s,% d-membered total amount of ' % (MONEY1, Money))
             BREAK 
        the else :
             Print ( ' recharge failed. Please enter the number ' )

# Show merchandise

def show_goods():
    print('序号  名称  价格')
    for index, dic in enumerate(goods_list, start=1):
        print(index, dic['name'].rjust(6), str(dic['price']).rjust(5))

#Add to cart

DEF Shopping (sn):
     # This already exists inside the shopping cart 
    IF sn in CAR:
        CAR [Sn] [ ' AMOUNT ' ] +. 1 =
     # does not exist, create a data 
    the else :
        car[sn] = {
            'name': goods_list[sn - 1]['name'],
            'price': goods_list[sn - 1]['price'],
            'amount': 1
        }
    Print ( ' Add cart success ' )
     Print ( ' No. Name Price Quantity Total ' )
     Print (sn, CAR [sn] [ ' name ' ] .rjust (6), str (CAR [sn] [ ' . price ' ] ) .rjust (. 5), STR (CAR [Sn] [ ' AMOUNT ' ]). the rjust (. 4 ),
          str(car[sn]['price'] * car[sn]['amount']).rjust(6))

# Show cart

def show_car():
    Total = 0
     Print ( ' [=================== cart detail below ===================] ' )
     Print ( ' number name Unit quantity total ' )
     for K, DIC in car.items ():
         Print (K, DIC [ ' name ' ] .rjust (. 6), STR (DIC [ ' . price ' ]). the rjust (. 5), STR (DIC [ ' AMOUNT ' ]). the rjust (. 4 ),
              str(dic['price'] * dic['amount']).rjust(6))
        total += dic['price'] * dic['amount']
    return total

# Display of goods purchased

DEF show_shopping ():
     Print ( ' [=================== your purchase details are as follows ================ ===] ' )
     Print ( ' number name Unit quantity total ' )
     for K, DIC in car.items ():
         Print (K, DIC [ ' name ' ] .rjust (. 6), STR (DIC [ ' . price ' ]). the rjust (. 5), STR (DIC [ ' AMOUNT ' ]). the rjust (. 4 ),
              str (dic [ ' . price ' ] * dic [ ' AMOUNT ' ]). rjust (6 ))
     Print ( ' shopping success! ' )

# drop out

DEF quit ():
     , Ltd. Free Join Flag
     Print ( ' [=================== always welcome ================ ===] ' )
    flag = False

# Delete item

def del_goods(sn):
    if sn.isdigit():
        sn = int(sn)
        if 0 < sn <= len(goods_list):
            car[sn]['amount'] -= 1
            if car[sn]['amount'] == 0:
                car.pop(sn)
        else:
            error2()
    else:
        ERROR1 ()

# Settlement

def jiesuan():
    global flag
    while 1:
        Total = show_car ()
         Print ( ' your current amount is% d yuan, into your cart's total commodity price of RMB% d ' % (Money, Total))

        # Enough money, you can pay 
        IF Money - Total> = 0:
            RES = the INPUT ( ' confirming the purchase, press y, according to q end the program, press any key to continue shopping ' ) .strip ()
             IF res.upper () == ' the Y- ' :
                 Print ( ' purchase is successful, your remaining% d yuan ' % (Money - Total))
                show_shopping()
                quit()
                break
            elif res.upper() == 'Q':
                quit()
                Flag = False
                 BREAK 
            the else :
                 BREAK 
        # enough money, delete some commodities 
        the else :
            RES = the INPUT ( ' your balance is insufficient, please delete some of the goods or recharge d c ' )
             IF res.upper () == ' D ' :
                sn = the INPUT ( ' Please enter the article number you want to delete: ' ) .strip ()
                 # remove items 
                del_goods (sn)
             elif res.upper () == ' C ' :
                chongzhi ()

# Some error function

DEF ERROR1 ():
     Print ( ' the options you entered does not exist ' )


DEF Error2 ():
     Print ( ' option you entered is out of range ' )

# Program entry

IF  __name__ == ' __main__ ' :
     Print ( ' [=================== Welcome ** Mall ============= ======] ' )
     # 1 top- 
    Chongzhi ()
     # 2. display of goods 
    show_goods ()
     # 3. start shopping 
    Flag = True
     the while Flag:
        sn = the INPUT ( ' Please enter the number you want to purchase goods :( settlement by n, press q to exit) ' ) .strip ()
         IF sn.isdigit ():
            sn = int(sn)
            if 0 < sn <= len(goods_list):
                # 购物
                shopping(sn)
            else:
                error2()
        elif sn.upper() == 'Q':
            quit()
        elif sn.upper() == 'N':
            jiesuan ()
        else:
            ERROR1 ()

summary:

1. Global variables used in the flag while flag in accordance with the wording before I would while True: After written like this, if they were in the loop

(1) if it can not meet certain conditions need to exit the loop, there is no way to do, write a variable, then it is a good control loop access, flag = 0, quit.

Such as:

flag = 1

while flag：

if(i<5):

flag=0

After executing the condition if, it will be out of the loop.

(2) the second case

flag = 1

while flag：

for in ilistvar:

　　pass

　　flag = 0

　　break

如果遇到执行循环之后想跳出大循环的这种情况，需要在内部循环中先使用break，跳出当前玄幻，再次循环的时候flag=0，就会立马退出。

2.程序中的全局变量money，flag 全局变量若要在函数里面就行修改的时候必须使用关键字，global。

3,.判断字符串中是否是纯数字字符串函数isdigit(),还有在字符串前面添加空白间隔字符，rjust().

        if sn.isdigit():
            sn = int(sn)
            if 0 < sn <= len(goods_list):
                # 购物
                shopping(sn)
            else:
                error2()
        elif sn.upper() == 'Q':
            quit()
        elif sn.upper() == 'N':
            jiesuan()
        else:
            error1()
思路很重要，一定要清楚。多成判断，处理每一层。
5.enumerate(可迭代数据，起始值) 返回的是一个个元祖索引和值的小元祖。
for k,v enumerate(XX):
　　print(k,v)
6.程序先考虑大体思路，然后可以从怎么去使用入手写程序。
7.本题程序，购物车的构造，以及商品列表的构造都是需要注意的。